The study of the Cost Dynamics of Critical Illness contains two major components: 1) a retrospective analysis of variations in costs and services experienced by critically ill patients at University Hospital, and 2) a prospective analysis of physician decision making for managing the critically ill. The purpose of the study is to provide information to policy makers about the determinants of expenditures for critical illness by (1) providing disaggregated estimates of expenditures on the critically ill, (2) determining the contribution of socioeconomic variables to variations in the costs of care for the critically ill and (3) delineating the physician decision model for treating the critically ill. A retrospective analysis of all patients admitted to critical care units at University Hospital over a two-year period from October 1, 1978 to September 27, 1980 will be completed during the first project year. A prospective analysis of treatment decisions of all patients admitted to the same units during a one-year period, February 1, 1981 to January 31, 1982 will be conducted during the second project year. Physician predisposition to "aggressive" or "conservative" treatment will be derived from measures of their attitudes about the ethics, social responsibility, and organizational context of treatment of critically and terminally ill patients. Circumstances of patients admission to the unit, the decision environment, and the physician's prognosis in the first 24 hours will also be used to model physician decision making and to expand analysis of cost variations.